Hi,
So, my wife had been BUGGING me to make the pre-existing egress window match the rest of the ones we just put in. No big deal I thought, rip out the wood on the bottom & sides between the window and the wall (11" w x 63"L) sand it then finish it... When I went to go remove it many of the nails were rusted and the plywood was starting to Rot (plywood really?) also the piece of plywood under that is also a bit rotten in the corners.... Is it normal the egress window is less than 15 years old? I figured it could be just because it was ply wood and the side by the window wasn't poly'd or anything, just the top was painted (and cracked)... So I bought some oak pieces so I could stain & poly them to put them in and I get to thinking if there was something else I should do to make it good or not. Anyone have any other suggestions? My table saw is waiting to cut these to size until I hear any suggestions, or tomorrow evening whichever comes first .

There was also missing insulation but not much around the sides but on one side I felt a nice winter draft so I was planning to shove some more in to fix that problem.

Codensation, warm moist air getting to cold area and moisture condensing, check out the wood structure below. If you have caught this early you may consider treating what you can see with a copper based treatment.